Question about patching a hole in a 50 gallon diesel tank

[whall]

My dad somehow ran our forklift fork through the back of the fuel tank. Not sure how he did it, I walked away for a couple minutes then looked back and he had run in to it.

The tank is an L-shape tank made to go under a tool box in the back of a truck. The hole is good size 6-8" long and about 2" from top to bottom. Luckily the tank was empty

I was thinking I would pull the hole out the best I could and take a piece of plate bigger than the hole and mig weld it to seal the hole.

I know that diesel isn't as readily explosive as gasoline but is still dangerous, what would be the best way to prep the tank before welding?

[Smokin Mike]

First question is; Is the tank aluminum? Most truck bed tanks are. If so, are you setup with a spoolgun and gas to weld aluminum?
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My current cookers: 80 gallon vertical tank
The Ultimate New Braunfels Makeover

[whall]

[Gulf]

[k.a.m.]

Wash the tank out with a good de-greaser at least twice, if you can still smell diesel clean it more then fill it with water to within an inch of the hole and apply the patch.
Since it is on the top of the L shaped tank you will be welding two vertical passes because it is sitting up. If you are not efficient at vertical welding find someone that is.
I can not stress enough if you are not completely confident about the tanks explosive state then do not proceed.
In my younger not so smart days I thought I would see how much fuel was left in a 500 gall tank. With no flash light handy I used my zippo lighter. I lost all the hair on my face, there were four 4" PVC caps on top. We found two about 100' away the other two were never found. I am lucky to be here to explain this.
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Always remember slow and steady wins the race.

Hybrid Cooker

[whall]

Thanks for the replies. My dad just decided to buy another tank. I might just clean the tank and let it sit a while with all the plugs out, then fix it for a spare later.

k.a.m. you are one lucky guy, wow